Soooo ... a quick preliminary update on my Sirrus X Comp.
As I've mentioned a couple times here, the FS cartridge on mine was defective from the get-go (June of this year): noisy, and with a distinct metallic 'click' whenever it neared full compression. LBS tried a number of different things, to no avail, so ordered a replacement under warranty.
I asked for the version of the cartridge that was on the original Roubaix -- linear, not progressive, spring -- as my bike is and will be used as a 'road bike'. The replacement was done today, and when I went to pick up my bike --
What Specialized sent was the Future Shock 2.0 cartridge, as one gets with the top-end 2020 Roubaix: full hydraulic damping w/a dial that goes from full-open to almost (not quite) lockout. No 'booster springs'. Retrofit more or less seamlessly into my bike with a bit of fiddling; no major bodges required. Initial impressions (short ride home): utterly silent; buttery/silky smooth; looks nicer; ruts/imperfections etc. absorbed fluidly. A complete transformation of the bike, which now 'feels' like what I was expecting when I ordered it.
So: with that, and with change to Roubaix Pro 32 tires, and with brakes sorted: bliss.
I'll update this with a fuller report, and pics, after a few more kms.